Just seems modding is a 1 click process to max the car out.
If you use the auto tuning option, sure. You can also select your own parts and make your own choices on how to use the available PI for your target class - do you make sacrifices on grip and weight to run more power, if its an off road / rally build how much on road ability do you forgo etc, and then further tuning if you've fitted tunable parts like race / drift offroad suspension, differentals, race transmission, race brakes, adjustable aero etc.
Its as in depth as you want it to be really.
You shouldn't be just slapping every part on a car, especially on slower cars where doing so will leave you somewhere in the middle of a performance class and therefore uncompetitive. If a car "only" makes S1/850 with everything on it then its never going to be a competitive S1 car, optimise the tune for A/800 instead.